GM Corvette 1963-1982 Repair Guide

Bleeding the Brake System

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PROCEDURES



See Figures 1, 2 and 3

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Fig. Fig. 1: A special wrench is available to loosen the bleeder screws



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Fig. Fig. 2: When bleeding rear disc brakes, first open and bleed the inner valve ...



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Fig. Fig. 3: ... then open and bleed the outer valve


WARNING
Clean, high quality brake fluid is essential to the safe and proper operation of the brake system. You should always buy the highest quality brake fluid that is available. If the brake fluid becomes contaminated, drain and flush the system, then refill the master cylinder with new fluid. Never reuse any brake fluid. Any brake fluid that is removed from the system should be discarded.

The hydraulic brake system must be bled any time one of the lines is disconnected or air enters the system. This may be done manually or by the pressure method. For vehicles equipped with drum brakes the correct bleeding sequence is: left rear wheel cylinder, right rear, right front, left front.

For vehicles equipped with four wheel disc brakes, the correct bleeding sequence is: left rear inner, left rear outer, right rear inner, right rear outer, left front and right front.

The manufacturer recommends that the entire hydraulic system be thoroughly flushed with clean brake fluid whenever new parts are installed in the hydraulic system. Flushing is also recommended if there is any doubt as to the grade of fluid in the system. If fluid has been used which contains the slightest trace of mineral oil, all rubber parts that have been subjected to the contaminated fluid should be replaced. When bleeding the rear brake system, the front of the car should be raised higher than the rear. This will position the bleeder valve near the 12 oclock position and prevent air from being trapped in the caliper.

Pressure Bleeding

  1. Clean the top of the master cylinder, remove the cover, and attach the pressure bleeding adapter.
  2.  
  3. Check the pressure bleeder reservoir for correct pressure and fluid level, then open the release valve.
  4.  
  5. Fasten a bleeder hose to the wheel cylinder bleeder nipple and submerge the free end of the hose in a transparent receptacle. The receptacle should contain enough brake fluid to cover the open end of the hose.
  6.  
  7. Open the wheel cylinder bleeder nipple and allow the fluid to flow until all bubbles disappear and an uncontaminated flow exists.
  8.  
  9. Close the nipple, remove the bleeder hose and repeat the procedure on the other wheel cylinders according to the bleeding sequence.
  10.  

Manual Bleeding

An alternative to the pressure method of bleeding requires two people to perform: one to depress the brake pedal and the other to open the bleeder nipples.

  1. Observe the cleaning operation of the pressure method, then remove the cover and fill the reservoir.
  2.  
  3. Attach a bleeder hose and clear container as before.
  4.  
  5. Have the assistant depress the brake pedal to the floor, and then pause until fluid flow ceases and the bleeder nipple is closed.
  6.  
  7. Allow the pedal to return and repeat the procedure until a steady, bubble-free flow is seen.
  8.  
  9. Secure the nipple and move to the other wheels in the correct sequence.
  10.  
  11. Periodically check the master cylinder for an adequate supply of fluid. If the reservoir runs dry, air will enter the system and bleeding will have to be done again.
  12.  

 
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